/**
 * @file
 * Sequential API Main thread module
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */

#include "lwip/opt.h"

#if !NO_SYS /* don't build if not configured for use in lwipopts.h */

#include "lwip/priv/tcpip_priv.h"
#include "lwip/sys.h"
#include "lwip/memp.h"
#include "lwip/mem.h"
#include "lwip/init.h"
#include "lwip/ip.h"
#include "lwip/pbuf.h"
#include "lwip/etharp.h"
#include "netif/ethernet.h"

#define TCPIP_MSG_VAR_REF(name) API_VAR_REF(name)
#define TCPIP_MSG_VAR_DECLARE(name) API_VAR_DECLARE(struct tcpip_msg, name)
#define TCPIP_MSG_VAR_ALLOC(name)                                              \
    API_VAR_ALLOC(struct tcpip_msg, MEMP_TCPIP_MSG_API, name, ERR_MEM)
#define TCPIP_MSG_VAR_FREE(name) API_VAR_FREE(MEMP_TCPIP_MSG_API, name)

/* global variables */
static tcpip_init_done_fn tcpip_init_done;
static void *tcpip_init_done_arg;
static sys_mbox_t tcpip_mbox;

#if LWIP_TCPIP_CORE_LOCKING
/** The global semaphore to lock the stack. */
sys_mutex_t lock_tcpip_core;
#endif /* LWIP_TCPIP_CORE_LOCKING */

static void tcpip_thread_handle_msg(struct tcpip_msg *msg);

#if !LWIP_TIMERS

/** Wait for a message with timers disabled (e.g. pass a timer-check trigger
 * into tcpip_thread) */
static void tcpip_mbox_fetch(sys_mbox_t *mbox, void **msg) {
    LWIP_ASSERT_CORE_LOCKED();

    UNLOCK_TCPIP_CORE();
    sys_mbox_fetch(mbox, msg);
    LOCK_TCPIP_CORE();
}

#else  /* !LWIP_TIMERS */

/**
 * Wait (forever) for a message to arrive in an mbox.
 * While waiting, timeouts are processed.
 *
 * @param mbox the mbox to fetch the message from
 * @param msg the place to store the message
 */
static void tcpip_mbox_fetch(sys_mbox_t *mbox, void **msg) {
    u32_t sleeptime, res;

again:
    LWIP_ASSERT_CORE_LOCKED();

    sleeptime = sys_timeouts_sleeptime();
    if (sleeptime == SYS_TIMEOUTS_SLEEPTIME_INFINITE) {
        UNLOCK_TCPIP_CORE();
        sys_arch_mbox_fetch(mbox, msg, 0);
        LOCK_TCPIP_CORE();
        return;
    } else if (sleeptime == 0) {
        sys_check_timeouts();
        /* We try again to fetch a message from the mbox. */
        goto again;
    }

    UNLOCK_TCPIP_CORE();
    res = sys_arch_mbox_fetch(mbox, msg, sleeptime);
    LOCK_TCPIP_CORE();
    if (res == SYS_ARCH_TIMEOUT) {
        /* If a SYS_ARCH_TIMEOUT value is returned, a timeout occurred
           before a message could be fetched. */
        sys_check_timeouts();
        /* We try again to fetch a message from the mbox. */
        goto again;
    }
}
#endif /* !LWIP_TIMERS */

/**
 * The main lwIP thread. This thread has exclusive access to lwIP core functions
 * (unless access to them is not locked). Other threads communicate with this
 * thread using message boxes.
 *
 * It also starts all the timers to make sure they are running in the right
 * thread context.
 *
 * @param arg unused argument
 */
static void tcpip_thread(void *arg) {
    struct tcpip_msg *msg;
    LWIP_UNUSED_ARG(arg);

    LWIP_MARK_TCPIP_THREAD();

    LOCK_TCPIP_CORE();
    if (tcpip_init_done != NULL) {
        tcpip_init_done(tcpip_init_done_arg);
    }

    while (1) { /* MAIN Loop */
        LWIP_TCPIP_THREAD_ALIVE();
        /* wait for a message, timeouts are processed while waiting */
        tcpip_mbox_fetch(&tcpip_mbox, (void **)&msg);
        if (msg == NULL) {
            LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: invalid message: NULL\n"));
            LWIP_ASSERT("tcpip_thread: invalid message", 0);
            continue;
        }
        tcpip_thread_handle_msg(msg);
    }
}

/* Handle a single tcpip_msg
 * This is in its own function for access by tests only.
 */
static void tcpip_thread_handle_msg(struct tcpip_msg *msg) {
    switch (msg->type) {
#if !LWIP_TCPIP_CORE_LOCKING
    case TCPIP_MSG_API:
        LWIP_DEBUGF(TCPIP_DEBUG,
                    ("tcpip_thread: API message %p\n", (void *)msg));
        msg->msg.api_msg.function(msg->msg.api_msg.msg);
        break;
    case TCPIP_MSG_API_CALL:
        LWIP_DEBUGF(TCPIP_DEBUG,
                    ("tcpip_thread: API CALL message %p\n", (void *)msg));
        msg->msg.api_call.arg->err =
            msg->msg.api_call.function(msg->msg.api_call.arg);
        sys_sem_signal(msg->msg.api_call.sem);
        break;
    case TCPIP_MSG_CALLBACK_STATIC_WAIT:
        LWIP_DEBUGF(TCPIP_DEBUG,
                    ("tcpip_thread: CALLBACK WAIT message %p\n", (void *)msg));
        msg->msg.cb_wait.function(msg->msg.cb_wait.ctx);
        sys_sem_signal(msg->msg.cb_wait.sem);
        break;
#endif /* !LWIP_TCPIP_CORE_LOCKING */

#if !LWIP_TCPIP_CORE_LOCKING_INPUT
    case TCPIP_MSG_INPKT:
        LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: PACKET %p\n", (void *)msg));
        if (msg->msg.inp.input_fn(msg->msg.inp.p, msg->msg.inp.netif) !=
            ERR_OK) {
            pbuf_free(msg->msg.inp.p);
        }
        memp_free(MEMP_TCPIP_MSG_INPKT, msg);
        break;
#endif /* !LWIP_TCPIP_CORE_LOCKING_INPUT */

#if LWIP_TCPIP_TIMEOUT && LWIP_TIMERS
    case TCPIP_MSG_TIMEOUT:
        LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: TIMEOUT %p\n", (void *)msg));
        sys_timeout(msg->msg.tmo.msecs, msg->msg.tmo.h, msg->msg.tmo.arg);
        memp_free(MEMP_TCPIP_MSG_API, msg);
        break;
    case TCPIP_MSG_UNTIMEOUT:
        LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: UNTIMEOUT %p\n", (void *)msg));
        sys_untimeout(msg->msg.tmo.h, msg->msg.tmo.arg);
        memp_free(MEMP_TCPIP_MSG_API, msg);
        break;
#endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */

    case TCPIP_MSG_CALLBACK:
        LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: CALLBACK %p\n", (void *)msg));
        msg->msg.cb.function(msg->msg.cb.ctx);
        memp_free(MEMP_TCPIP_MSG_API, msg);
        break;

    case TCPIP_MSG_CALLBACK_STATIC:
        LWIP_DEBUGF(TCPIP_DEBUG,
                    ("tcpip_thread: CALLBACK_STATIC %p\n", (void *)msg));
        msg->msg.cb.function(msg->msg.cb.ctx);
        break;

    default:
        LWIP_DEBUGF(TCPIP_DEBUG,
                    ("tcpip_thread: invalid message: %d\n", msg->type));
        LWIP_ASSERT("tcpip_thread: invalid message", 0);
        break;
    }
}

#ifdef TCPIP_THREAD_TEST
/** Work on queued items in single-threaded test mode */
int tcpip_thread_poll_one(void) {
    int ret = 0;
    struct tcpip_msg *msg;

    if (sys_arch_mbox_tryfetch(&tcpip_mbox, (void **)&msg) != SYS_MBOX_EMPTY) {
        LOCK_TCPIP_CORE();
        if (msg != NULL) {
            tcpip_thread_handle_msg(msg);
            ret = 1;
        }
        UNLOCK_TCPIP_CORE();
    }
    return ret;
}
#endif

/**
 * Pass a received packet to tcpip_thread for input processing
 *
 * @param p the received packet
 * @param inp the network interface on which the packet was received
 * @param input_fn input function to call
 */
err_t tcpip_inpkt(struct pbuf *p, struct netif *inp, netif_input_fn input_fn) {
#if LWIP_TCPIP_CORE_LOCKING_INPUT
    err_t ret;
    LWIP_DEBUGF(TCPIP_DEBUG,
                ("tcpip_inpkt: PACKET %p/%p\n", (void *)p, (void *)inp));
    LOCK_TCPIP_CORE();
    ret = input_fn(p, inp);
    UNLOCK_TCPIP_CORE();
    return ret;
#else  /* LWIP_TCPIP_CORE_LOCKING_INPUT */
    struct tcpip_msg *msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_INPKT);
    if (msg == NULL) {
        return ERR_MEM;
    }

    msg->type = TCPIP_MSG_INPKT;
    msg->msg.inp.p = p;
    msg->msg.inp.netif = inp;
    msg->msg.inp.input_fn = input_fn;
    if (sys_mbox_trypost(&tcpip_mbox, msg) != ERR_OK) {
        memp_free(MEMP_TCPIP_MSG_INPKT, msg);
        return ERR_MEM;
    }
    return ERR_OK;
#endif /* LWIP_TCPIP_CORE_LOCKING_INPUT */
}

/**
 * @ingroup lwip_os
 * Pass a received packet to tcpip_thread for input processing with
 * ethernet_input or ip_input. Don't call directly, pass to netif_add()
 * and call netif->input().
 *
 * @param p the received packet, p->payload pointing to the Ethernet header or
 *          to an IP header (if inp doesn't have NETIF_FLAG_ETHARP or
 *          NETIF_FLAG_ETHERNET flags)
 * @param inp the network interface on which the packet was received
 */
err_t tcpip_input(struct pbuf *p, struct netif *inp) {
#if LWIP_ETHERNET
    if (inp->flags & (NETIF_FLAG_ETHARP | NETIF_FLAG_ETHERNET)) {
        return tcpip_inpkt(p, inp, ethernet_input);
    } else
#endif /* LWIP_ETHERNET */
        return tcpip_inpkt(p, inp, ip_input);
}

/**
 * @ingroup lwip_os
 * Call a specific function in the thread context of
 * tcpip_thread for easy access synchronization.
 * A function called in that way may access lwIP core code
 * without fearing concurrent access.
 * Blocks until the request is posted.
 * Must not be called from interrupt context!
 *
 * @param function the function to call
 * @param ctx parameter passed to f
 * @return ERR_OK if the function was called, another err_t if not
 *
 * @see tcpip_try_callback
 */
err_t tcpip_callback(tcpip_callback_fn function, void *ctx) {
    struct tcpip_msg *msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
    if (msg == NULL) {
        return ERR_MEM;
    }

    msg->type = TCPIP_MSG_CALLBACK;
    msg->msg.cb.function = function;
    msg->msg.cb.ctx = ctx;

    sys_mbox_post(&tcpip_mbox, msg);
    return ERR_OK;
}

/**
 * @ingroup lwip_os
 * Call a specific function in the thread context of
 * tcpip_thread for easy access synchronization.
 * A function called in that way may access lwIP core code
 * without fearing concurrent access.
 * Does NOT block when the request cannot be posted because the
 * tcpip_mbox is full, but returns ERR_MEM instead.
 * Can be called from interrupt context.
 *
 * @param function the function to call
 * @param ctx parameter passed to f
 * @return ERR_OK if the function was called, another err_t if not
 *
 * @see tcpip_callback
 */
err_t tcpip_try_callback(tcpip_callback_fn function, void *ctx) {
    struct tcpip_msg *msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
    if (msg == NULL) {
        return ERR_MEM;
    }

    msg->type = TCPIP_MSG_CALLBACK;
    msg->msg.cb.function = function;
    msg->msg.cb.ctx = ctx;

    if (sys_mbox_trypost(&tcpip_mbox, msg) != ERR_OK) {
        memp_free(MEMP_TCPIP_MSG_API, msg);
        return ERR_MEM;
    }
    return ERR_OK;
}

#if LWIP_TCPIP_TIMEOUT && LWIP_TIMERS
/**
 * call sys_timeout in tcpip_thread
 *
 * @param msecs time in milliseconds for timeout
 * @param h function to be called on timeout
 * @param arg argument to pass to timeout function h
 * @return ERR_MEM on memory error, ERR_OK otherwise
 */
err_t tcpip_timeout(u32_t msecs, sys_timeout_handler h, void *arg) {
    struct tcpip_msg *msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
    if (msg == NULL) {
        return ERR_MEM;
    }

    msg->type = TCPIP_MSG_TIMEOUT;
    msg->msg.tmo.msecs = msecs;
    msg->msg.tmo.h = h;
    msg->msg.tmo.arg = arg;
    sys_mbox_post(&tcpip_mbox, msg);
    return ERR_OK;
}

/**
 * call sys_untimeout in tcpip_thread
 *
 * @param h function to be called on timeout
 * @param arg argument to pass to timeout function h
 * @return ERR_MEM on memory error, ERR_OK otherwise
 */
err_t tcpip_untimeout(sys_timeout_handler h, void *arg) {
    struct tcpip_msg *msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
    if (msg == NULL) {
        return ERR_MEM;
    }

    msg->type = TCPIP_MSG_UNTIMEOUT;
    msg->msg.tmo.h = h;
    msg->msg.tmo.arg = arg;
    sys_mbox_post(&tcpip_mbox, msg);
    return ERR_OK;
}
#endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */

/**
 * Sends a message to TCPIP thread to call a function. Caller thread blocks on
 * on a provided semaphore, which is NOT automatically signalled by TCPIP
 * thread, this has to be done by the user. It is recommended to use
 * LWIP_TCPIP_CORE_LOCKING since this is the way with least runtime overhead.
 *
 * @param fn function to be called from TCPIP thread
 * @param apimsg argument to API function
 * @param sem semaphore to wait on
 * @return ERR_OK if the function was called, another err_t if not
 */
err_t tcpip_send_msg_wait_sem(tcpip_callback_fn fn, void *apimsg,
                              sys_sem_t *sem) {
#if LWIP_TCPIP_CORE_LOCKING
    LWIP_UNUSED_ARG(sem);
    LOCK_TCPIP_CORE();
    fn(apimsg);
    UNLOCK_TCPIP_CORE();
    return ERR_OK;
#else  /* LWIP_TCPIP_CORE_LOCKING */
    TCPIP_MSG_VAR_DECLARE(msg);

    LWIP_ASSERT("semaphore not initialized", sys_sem_valid(sem));
    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    TCPIP_MSG_VAR_ALLOC(msg);
    TCPIP_MSG_VAR_REF(msg).type = TCPIP_MSG_API;
    TCPIP_MSG_VAR_REF(msg).msg.api_msg.function = fn;
    TCPIP_MSG_VAR_REF(msg).msg.api_msg.msg = apimsg;
    sys_mbox_post(&tcpip_mbox, &TCPIP_MSG_VAR_REF(msg));
    sys_arch_sem_wait(sem, 0);
    TCPIP_MSG_VAR_FREE(msg);
    return ERR_OK;
#endif /* LWIP_TCPIP_CORE_LOCKING */
}

/**
 * Synchronously calls function in TCPIP thread and waits for its completion.
 * It is recommended to use LWIP_TCPIP_CORE_LOCKING (preferred) or
 * LWIP_NETCONN_SEM_PER_THREAD.
 * If not, a semaphore is created and destroyed on every call which is usually
 * an expensive/slow operation.
 * @param fn Function to call
 * @param call Call parameters
 * @return Return value from tcpip_api_call_fn
 */
err_t tcpip_api_call(tcpip_api_call_fn fn, struct tcpip_api_call_data *call) {
#if LWIP_TCPIP_CORE_LOCKING
    err_t err;
    LOCK_TCPIP_CORE();
    err = fn(call);
    UNLOCK_TCPIP_CORE();
    return err;
#else /* LWIP_TCPIP_CORE_LOCKING */
    TCPIP_MSG_VAR_DECLARE(msg);

#if !LWIP_NETCONN_SEM_PER_THREAD
    err_t err = sys_sem_new(&call->sem, 0);
    if (err != ERR_OK) {
        return err;
    }
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    TCPIP_MSG_VAR_ALLOC(msg);
    TCPIP_MSG_VAR_REF(msg).type = TCPIP_MSG_API_CALL;
    TCPIP_MSG_VAR_REF(msg).msg.api_call.arg = call;
    TCPIP_MSG_VAR_REF(msg).msg.api_call.function = fn;
#if LWIP_NETCONN_SEM_PER_THREAD
    TCPIP_MSG_VAR_REF(msg).msg.api_call.sem = LWIP_NETCONN_THREAD_SEM_GET();
#else  /* LWIP_NETCONN_SEM_PER_THREAD */
    TCPIP_MSG_VAR_REF(msg).msg.api_call.sem = &call->sem;
#endif /* LWIP_NETCONN_SEM_PER_THREAD */
    sys_mbox_post(&tcpip_mbox, &TCPIP_MSG_VAR_REF(msg));
    sys_arch_sem_wait(TCPIP_MSG_VAR_REF(msg).msg.api_call.sem, 0);
    TCPIP_MSG_VAR_FREE(msg);

#if !LWIP_NETCONN_SEM_PER_THREAD
    sys_sem_free(&call->sem);
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

    return call->err;
#endif /* LWIP_TCPIP_CORE_LOCKING */
}

/**
 * @ingroup lwip_os
 * Allocate a structure for a static callback message and initialize it.
 * The message has a special type such that lwIP never frees it.
 * This is intended to be used to send "static" messages from interrupt context,
 * e.g. the message is allocated once and posted several times from an IRQ
 * using tcpip_callbackmsg_trycallback().
 * Example usage: Trigger execution of an ethernet IRQ DPC routine in lwIP
 * thread context.
 *
 * @param function the function to call
 * @param ctx parameter passed to function
 * @return a struct pointer to pass to tcpip_callbackmsg_trycallback().
 *
 * @see tcpip_callbackmsg_trycallback()
 * @see tcpip_callbackmsg_delete()
 */
struct tcpip_callback_msg *tcpip_callbackmsg_new(tcpip_callback_fn function,
                                                 void *ctx) {
    struct tcpip_msg *msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
    if (msg == NULL) {
        return NULL;
    }
    msg->type = TCPIP_MSG_CALLBACK_STATIC;
    msg->msg.cb.function = function;
    msg->msg.cb.ctx = ctx;
    return (struct tcpip_callback_msg *)msg;
}

/**
 * @ingroup lwip_os
 * Free a callback message allocated by tcpip_callbackmsg_new().
 *
 * @param msg the message to free
 *
 * @see tcpip_callbackmsg_new()
 */
void tcpip_callbackmsg_delete(struct tcpip_callback_msg *msg) {
    memp_free(MEMP_TCPIP_MSG_API, msg);
}

/**
 * @ingroup lwip_os
 * Try to post a callback-message to the tcpip_thread tcpip_mbox.
 *
 * @param msg pointer to the message to post
 * @return sys_mbox_trypost() return code
 *
 * @see tcpip_callbackmsg_new()
 */
err_t tcpip_callbackmsg_trycallback(struct tcpip_callback_msg *msg) {
    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));
    return sys_mbox_trypost(&tcpip_mbox, msg);
}

/**
 * @ingroup lwip_os
 * Try to post a callback-message to the tcpip_thread mbox.
 * Same as @ref tcpip_callbackmsg_trycallback but calls
 * sys_mbox_trypost_fromisr(), mainly to help FreeRTOS, where calls differ
 * between task level and ISR level.
 *
 * @param msg pointer to the message to post
 * @return sys_mbox_trypost_fromisr() return code (without change, so this
 *         knowledge can be used to e.g. propagate "bool needs_scheduling")
 *
 * @see tcpip_callbackmsg_new()
 */
err_t tcpip_callbackmsg_trycallback_fromisr(struct tcpip_callback_msg *msg) {
    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));
    return sys_mbox_trypost_fromisr(&tcpip_mbox, msg);
}

/**
 * Sends a message to TCPIP thread to call a function. Caller thread blocks
 * until the function returns.
 * It is recommended to use LWIP_TCPIP_CORE_LOCKING (preferred) or
 * LWIP_NETCONN_SEM_PER_THREAD.
 * If not, a semaphore is created and destroyed on every call which is usually
 * an expensive/slow operation.
 *
 * @param function the function to call
 * @param ctx parameter passed to f
 * @return ERR_OK if the function was called, another err_t if not
 */
err_t tcpip_callback_wait(tcpip_callback_fn function, void *ctx) {
#if LWIP_TCPIP_CORE_LOCKING
    LOCK_TCPIP_CORE();
    function(ctx);
    UNLOCK_TCPIP_CORE();
    return ERR_OK;
#else  /* LWIP_TCPIP_CORE_LOCKING */
    err_t err;
    sys_sem_t sem;
    struct tcpip_msg msg;

    LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));

    err = sys_sem_new(&sem, 0);
    if (err != ERR_OK) {
        return err;
    }

    msg.type = TCPIP_MSG_CALLBACK_STATIC_WAIT;
    msg.msg.cb_wait.function = function;
    msg.msg.cb_wait.ctx = ctx;
    msg.msg.cb_wait.sem = &sem;
    sys_mbox_post(&tcpip_mbox, &msg);
    sys_arch_sem_wait(&sem, 0);
    sys_sem_free(&sem);
    return ERR_OK;
#endif /* LWIP_TCPIP_CORE_LOCKING */
}

/**
 * @ingroup lwip_os
 * Initialize this module:
 * - initialize all sub modules
 * - start the tcpip_thread
 *
 * @param initfunc a function to call when tcpip_thread is running and finished
 * initializing
 * @param arg argument to pass to initfunc
 */
void tcpip_init(tcpip_init_done_fn initfunc, void *arg) {
    lwip_init();

    tcpip_init_done = initfunc;
    tcpip_init_done_arg = arg;
    if (sys_mbox_new(&tcpip_mbox, TCPIP_MBOX_SIZE) != ERR_OK) {
        LWIP_ASSERT("failed to create tcpip_thread mbox", 0);
    }
#if LWIP_TCPIP_CORE_LOCKING
    if (sys_mutex_new(&lock_tcpip_core) != ERR_OK) {
        LWIP_ASSERT("failed to create lock_tcpip_core", 0);
    }
#endif /* LWIP_TCPIP_CORE_LOCKING */

    sys_thread_new(TCPIP_THREAD_NAME, tcpip_thread, NULL,
                   TCPIP_THREAD_STACKSIZE, TCPIP_THREAD_PRIO);
}

/**
 * Simple callback function used with tcpip_callback to free a pbuf
 * (pbuf_free has a wrong signature for tcpip_callback)
 *
 * @param p The pbuf (chain) to be dereferenced.
 */
static void pbuf_free_int(void *p) {
    struct pbuf *q = (struct pbuf *)p;
    pbuf_free(q);
}

/**
 * A simple wrapper function that allows you to free a pbuf from interrupt
 * context.
 *
 * @param p The pbuf (chain) to be dereferenced.
 * @return ERR_OK if callback could be enqueued, an err_t if not
 */
err_t pbuf_free_callback(struct pbuf *p) {
    return tcpip_try_callback(pbuf_free_int, p);
}

/**
 * A simple wrapper function that allows you to free heap memory from
 * interrupt context.
 *
 * @param m the heap memory to free
 * @return ERR_OK if callback could be enqueued, an err_t if not
 */
err_t mem_free_callback(void *m) { return tcpip_try_callback(mem_free, m); }

#endif /* !NO_SYS */
